Effects Of Hypoxia Induced Invasion Of Papillary Thyroid Carcinoma Cells Through MT

Objection To investigate the effects and potential mechanism of metallothioneins (MTs) induced by hypoxic circumstances on invasion potential in human papillary thyroid carcinoma (PTC).Methods PTC cells were cultured under hypoxic and normoxic circumstances; expression of MT, HIF-1α, SIP1 and E-cadherin were tested by Western blot and RT-PCR; invasion and migration ability were determined by Transwell/Matrigel assay. The expression levels of MT, HIF-la, SIP1 and MMP-9 were analyzed in 72 PTCs and 37 normal thyroid tissues using immunohistochemistry, and their correlations with the clinicopathological features were examined. BCPAP cells were transfected with MT2A-siRNA, MT2A-pcDNA3.1, and expression of MT, HIF-la, SIP1, E-cadherin and MMP-9 were measured by Western blot; invasion and migration ability were determined by Transwell/Matrigel assay.Results Under hypoxia, protein expression level of MT, HIF-la and SIP1 increase, mRNA expression level of MT and SIP1 increased. While the expression of E-cadherin decreased. The invasion and migration ability were promoted in hypoxic condition, compared to normoxic group (P<0.05). MT, HIF-1α, SIP1 and MMP-9 expression rates were 52.78%, 55.56%,51.39% and 54.17% in 72 PTC patients,significantly higher than normal thyroid tissues (P<0.01). High expression of MT, HIF-1α and SIP1 was correlated with lymph node metastasis (P<0.05). While high expression of MMP-9 was correlated with tumor size (P<0.05), the expression of MT was positively correlated with HIF-1α and SIP1 in PTC. The protein expression level of MT, HIF-1α, SIP1 and MMP-9 was down-regulated or up-regulated in BCPAP cell after being treated with MT2A-siRNA or MT2A-pcDNA3.1. However, E-cadherin protein expression level was up-regulated or down-regulated being treated with MT2 A-siRNA or MT2A-pcDNA3.1.Conclusion Hypoxia could up-regulate the expression of MT, SIP1 and down-regulate the expression of E-cadherin in PTC cell, and reinforce their invasion and migration ability. HIF-1α, SIP1 and MMP-9 expression in PTC samples have a closely correlation, which are related to cervical lymph node metastasis. To conclude, the expression of MTs induced by hypoxia maybe promote invasion in PTC.